This invention relates to a load indicator for an air cleaner associated with an air movement system operating in response to electrical energy supplied through a conducting circuit.
Normal blower operations such as in a furnace or air conditioning system designed for home use or the like generally operates in response to energizing current of a predetermined magnitude. When such fan is employed in conjunction with a clean air filter, the fan operates properly and the energizing current remains substantially constant. As the filter begins to collect dirt and lint, the blower moves less air, thereby causing a decrease in the load on the blower motor which has been found to decrease the magnitude of the energizing current. If the filter is not cleaned or replaced, it may become sufficiently clogged so as to substantially reduce the passage of air and thereby affecting the ability of the system to heat or cool the home or commercial establishment. In such situations, a sharp increase in energizing current well above the normal operating current level occurs which may tend to burn out the blower motor and cause severe damage.
One disclosed prior system senses, through the insertion of a current sensing resistor within the blower energizing circuit, an excessive current level flowing to the blower motor which generally occurs after the filter is severely contaminated which might otherwise burn out the fan motor through excessively high currents, such as suggested in U.S. Pat. No. 4,040,042 issued to Horst Mayer on Aug. 2, 1977.